• Title/Summary/Keyword: reservoir capacity

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Analysis on Hydrologic Stability of Agricultural Reservoir Using Probable Maximum Flood (최대가능홍수량 적용에 따른 농업용 저수지의 수문학적 안정성 분석)

  • Kim, Sang-Woo;Maeng, Seung-Jin
    • KCID journal
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    • v.17 no.2
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    • pp.28-34
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    • 2010
  • This study re-exams hydrologic stability on spillway outlet capacity of agricultural reservoirs using hydrologic data with current rainfall condition instead of project hydrologic data applied at design on Backgok reservoir located in Chungbuk province. It is concluded that Backgok reservoir is not hydrologically stable and therefore structural measures including the extension of spillway and non structural measures should be taken. Continuous basic plan for river maintenance including additional bank reinforcement to bottom river shall be carried out. Due to high peak flood with more than 290% compared to 200 year frequency probability flood which was design standard of the past in view of the results of calculating PMF according to revised design standard for reservoirs, there could a problem for securing rationality in case of applying PMF with design flood. Therefore, hydrological stability, construction, and maintenance cost shall be synthetically studied and reasonal application shall be made if the decision is made on applying PMF with design flood.

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Plausible grid size for a real time decision making system based 3D water quality model (실시간 수질관리도구로서의 3차원 수질모형의 최적 격자크기 산정)

  • Ahn, Ki-Hong
    • Journal of Environmental Impact Assessment
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    • v.20 no.4
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    • pp.575-583
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    • 2011
  • In this study, the plausible grid size was estimated to increase for efficiency of reservoir management using 3 dimensional water quality model. To validate utilization of a real time water quality management tool, ELCOM-CAEDYM model was applied to Soyang reservoir in korea. 100m grid size can represent the real topography and take out exact analysis results. $400{\times}400m$ grid can be easily used to analysis because of data capacity. Consequently, the grid size of 200m or 300m was recommended to establish 3D model considering the required simulation time and the irrelevance between horizontal grid size and vertical distribution for temperature and turbidity analysis.

Hydrological Drought Assessment of Agricultural Reservoirs based on SWSI in Geum River Basin (SWSI에 기반한 금강권역 농업용 저수지의 수문학적 가뭄평가)

  • Ahn, So-Ra;Park, Jong-Yoon;Jung, In-Kyun;Na, Sang-Jin;Kim, Seong-Joon
    • Journal of The Korean Society of Agricultural Engineers
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    • v.51 no.5
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    • pp.35-49
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    • 2009
  • This study proposes a method to evaluate agricultural reservoirs drought by modifying SWSI (Surface Water Supply Index). The method was applied to Geum river basin and the results were represented as spatially distributed information. The SWSI evaluates hydrological drought of watershed unit by selectively applying one or all of the components of snowpack, precipitation, streamflow and reservoir storage. South Korea has 22 % of agricultural area, and rice paddy covers 64 % among them. Usually paddy fields scattered along stream are irrigated by so many small agricultural reservoirs. It is difficult to evaluate agriculture drought by the little information and large number of agricultural reservoirs. In this study, seven agricultural reservoirs over 10 million ton storage capacity were selected in Geum river basin, and the SWSI was evaluated for both upstream and downstream of the reservoirs using 16 years data (1991-2006). Using the results, multiple regression analyses with precipitation and reservoir storage as variables were conducted and the equations were applied to other watersheds. The spatial results by applying regression equations showed that the severe and moderate drought conditions of July and September in 1994, June in 1995, and May in 2001 were well expressed by the watershed unit.

Analysis of Drainage Efficiency of Different Type of Drainage using Computational Fluid Dynamic Method (유동해석을 통한 배수지형태에 따른 배수효율분석)

  • Cho, Jung-Yeon;Go, Sun-Ho;Kim, Hong-Gun
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.16 no.2
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    • pp.34-43
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    • 2017
  • Large amounts of household water are required as common households change from the single-residence types of the past to group-residence types. Therefore, the management of reservoirs is urgently required to ensure the supply of clean household water to users. Important considerations for household water include the duration for which the water is stored in the reservoir, the disinfectant's dilution capacity, and the size of the reservoir to allow for the amount of water required for emergencies and firefighting. The drainage efficiency was analyzed in this study using computational fluid analysis for existing rectangular reservoirs and the newly proposed hexagonal reservoir. Thus, it was determined that the centrifugal force generated at the inlet was maintained until the outlet due to the approximately circular shape of the hexagonal reservoir. The findings of this study verified that the centrifugal force improved the flow rate by approximately 35% compared to existing rectangular reservoirs and that drainage was performed efficiently without stagnation zone.

Evaluation of Flood Control Capacity for Seongju Dam against Extreme Floods (이상강우에 대비한 성주댐의 홍수조절 능력 분석)

  • 권순국;한건연;서승덕;최혁준
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.45 no.6
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    • pp.109-118
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    • 2003
  • As a fundamental research to establish a safety operation plan for irrigation dams, this study presents hydrologic analysis conducted in Sungju Dam watershed based on various rainfall data. Especially those reservoirs without flood control feature are widely exposed to the risk of flooding, a safe and optimized operation program need to be improved against arbitrary flooding. In this study, reservoir routing program was developed and simulated for reservoir runoff estimation using WMS hydrology model. The model simulated the variations of reservoir elevation under the condition of open or closed emergency gate. In case of closed emergency gate, water surface elevation was given as 193.15 m, and this value exceeds the dam crest height by 1.65 m. When the emergency gate is open, the increment of water surface elevation is given as 192.01 m, and this value exceeds dam crest height by 0.57 m. As an alternative plan, dam height increase can be considered for flood control under the PMP (Probable Maximum Precipitation) condition. Since the dam size is relatively small compare to the watershed area, sound protection can be expected from the latter option rather than emergency gate installation.

Computational Fluid Dynamics Simulation of Flow Pattern Change in the Andong-Imha Reservoir Connecting Tunnel Due to Fish Exclusion Screens (어류 차단 스크린 설치에 따른 안동-임하호 연결터널 내 흐름변화에 대한 전산유체동역학 수치모의)

  • An, Sangdo
    • Journal of Korean Society on Water Environment
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    • v.30 no.5
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    • pp.477-485
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    • 2014
  • Imha Reservoir is connected to Andong Reservoir via a diversion tunnel allowing water to pass between. The diversion tunnel is equipped with screens to exclude exotic largemouth bass due to their predatory impacts on prey assemblages resulting in a degradation of species richness of local fish fauna and extinction of local fish populations in Korea. Flow pattern changes resulting from the fish screens and trash racks were investigated using a computational fluid dynamics (CFD) model. Numerical simulations showed that the decrease in the discharge capacity of the tunnel is approximately 8.6% and the headloss coefficient for fish screen at Andong intake tower was determined to be 1.5. In order not to allow the small fishes enough to pass through the wire openings enter into Imha Reservoir through tunnel, the velocity in the tunnel should be greater than 1.48 m/s which is a critical ascending velocity of the bass. This study suggests that it can keep the velocity higher enough to exclude largemouth bass when a gate opens with the condition of 1.0m difference in water stage between two reservoirs.

Hydrologic Safety Evaluation of Small Scale Reservoir by Simplified Assesment Method (간편법에 의한 소규모저수지의 수문학적 안전성 평가)

  • Lee, Joo-Heon;Yang, Seung-Man;Kim, Seong-Joon;Kang, Boo-Sik
    • Journal of The Korean Society of Agricultural Engineers
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    • v.53 no.2
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    • pp.9-17
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    • 2011
  • Based on the statistical annual report, there are 17,649 reservoirs are operating for the purpose of agricultural water supply in Korea. 58 % of entire agricultural reservoirs had been constructed before 1948 which indicate the termination of required service life and rest of those reservoirs have also exposed to the dam break risk by extreme flood event caused by current ongoing climate change. To prevent damages from dam failure accident of these risky small size dams, it is necessary to evaluate and manage the structural and hydrological safety of the reservoirs. In this study, a simplified evaluation method for hydrologic safety of dam is suggested by using Rational and Creager formula. Hydrologic safety of small scale dams has evaluated by calculating flood discharge capacity of the spillway and compares the results with design frequency of each reservoir. Applicability and stability of suggested simplified method have examined and reviewd by comparing the results from rainfall-runoff modeling with dam break simulation using HEC-HMS. Application results of developed methodology for three sample reservoirs show that simplified assessment method tends to calculate greater inflow to the reservoirs then HEC-HMS model which lead lowered hydrologic safety of reservoirs. Based on the results of application, it is expected that the developed methodology can be adapted as useful tool for small scale reservoir's hydrologic safety evaluation.

Improvement of Quantitative Condition Assessment Criteria for Reservoir Embankment Safety Inspection Considering Characteristics of Small Reservoirs in Korea (소규모 저수지의 특성을 고려한 제체 안전진단의 정량적 상태평가 기준 개선)

  • Jeon, Geonyeong;Bang, Donseok
    • Journal of The Korean Society of Agricultural Engineers
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    • v.63 no.5
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    • pp.27-38
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    • 2021
  • The physical condition assessment criteria of fill dam safety inspection are now weakly regulated and inappropriate for small agricultural reservoirs since these criteria have fundamental backgrounds suitable for large-scale dams. This study proposes the degree (critical values) of defects for the quantitative condition assessment of the embankment in order to prepare the condition assessment criteria for a small reservoir with a storage capacity of less than one (1) million cubic meters. The critical values of defects were calculated by applying the method that considers the size ratios based on the dimensional data of reservoirs, and the method of statistical analysis on the measured values of the defect degree which extracted from comprehensive annual reports on reservoir safety inspection. In comparison with the current criteria, the newly proposed critical values for each condition assessment item of the reservoir embankment are presented in paragraphs 4 and 6 of the conclusion. In addition, this study presents a method of displaying geometric figures to clarify the rating classification for condition assessment items with the two defect indicators.

Analysis of Water Supply Probability for Agricultural Reservoirs Considering Non-irrigation Period Precipitation using RCP Scenarios (RCP 시나리오 기반 비관개기 강수량을 고려한 농업용 저수지의 용수공급 확률 분석)

  • Bang, Jehong;Choi, Jin-Yong;Lee, Sang-Hyun
    • Journal of The Korean Society of Agricultural Engineers
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    • v.60 no.4
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    • pp.63-72
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    • 2018
  • The main function of an agricultural reservoir is to supply irrigation water to paddy rice fields in South Korea. Therefore, the operation of a reservoir is significantly affected by the phenology of paddy rice. For example, the early stage of irrigation season, a lot of irrigation water is required for transplanting rice. Therefore, water storage in the reservoir before irrigation season can be a key factor for sustainable irrigation, and it becomes more important under climate change situation. In this study, we analyzed the climate change impacts on reservoir storage rate at the beginning of irrigation period and simulated the reservoir storage, runoff, and irrigation water requirement under RCP scenarios. Frequency analysis was conducted with simulation results to analyze water supply probabilities of reservoirs. Water supply probability was lower in RCP 8.5 scenario than in RCP 4.5 scenario because of low precipitation in the non-irrigation period. Study reservoirs are classified into 5 groups by water supply probability. Reservoirs in group 5 showed more than 85 percentage probabilities to be filled up from half-filled condition during the non-irrigation period, whereas group 1 showed less than 5 percentages. In conclusion, reservoir capacity to catchment area ratio mainly affected water supply probability. If the ratio was high, reservoirs tended to have a low possibility to supply enough irrigation water amount.

Water Supply Capacity of the Keum River Barrage Dam Based on Inflow Scenario (유입량 시나리오에 따른 금강하구둑의 용수공급능력 분석)

  • Noh, Jae-Kyoung;Kim, Dae-Hyun
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 2003.10a
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    • pp.499-502
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    • 2003
  • Using the daily water balance model of the Keum River Barrage Dam, water supply capacity was analyzed. The scenario of reservoir inflow was selected to case with Daechung dam, case with no dam, case with Yongdam dams. Runoffs in 12 sub watersheds were simulated by the DAWAST model considered return flows.

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